An Aerosol Generating Device

ABSTRACT

An aerosol generating device includes a main body configured to receive an aerosol generating article. The main body includes an outer casing, an inner casing ( 20 ), and an inner cover. The inner cover is secured to a periphery of the inner casing to define a space between the inner surface of the inner cover and an inner surface of the inner casing. The aerosol generating device further includes an outer cover positioned over the inner cover and having an inner surface and an outer surface. The outer surface of the outer casing and the outer surface of the outer cover define an external surface of the aerosol generating device, and a periphery of the outer cover contacts a periphery of the outer casing so that the outer surface of the outer cover lies substantially flush with the outer surface of the outer casing to define a continuous external surface.

TECHNICAL FIELD

The present disclosure relates generally to an aerosol generating device, and more particularly to an aerosol generating device for heating an aerosol generating substrate to generate an aerosol for inhalation by a user. The present disclosure is particularly applicable to a portable (hand-held) aerosol generating device. Such devices may heat, rather than burn, an aerosol generating substrate by conduction, convection, and/or radiation, to generate an aerosol for inhalation.

TECHNICAL BACKGROUND

The popularity and use of reduced-risk or modified-risk devices (also known as vaporisers) has grown rapidly in recent years as an alternative to the use of traditional tobacco products. Various devices and systems are available that heat or warm aerosol generating substances to generate an aerosol for inhalation by a user.

One type of commonly available reduced-risk or modified-risk device is the heated substrate aerosol generating device, or so-called heat-not-burn device. Devices of this type generate an aerosol or vapour by heating an aerosol generating substrate to a temperature typically in the range 150° C. to 300° C. Heating the aerosol generating substrate to a temperature within this range, without burning or combusting the aerosol generating substrate, generates a vapour which typically cools and condenses to form an aerosol for inhalation by a user of the device.

Another type of commonly available reduced-risk or modified-risk device heats an aerosol generating liquid to generate a vapour that cools and condenses to form an aerosol which is then inhaled by the user. The aerosol generating liquid usually comprises nicotine, propylene glycol, glycerine, and flavourings.

Both types of aerosol generating device comprise a main body which houses an aerosol generating unit, and the main body can be formed by a plurality of component parts, such as one or more casing elements and cover elements. In order to ensure that the aerosol generating device has an aesthetic appearance which is acceptable to the user, there is a need to ensure a close fit between the component parts and the present disclosure seeks to address this need.

SUMMARY OF THE DISCLOSURE

According to a first aspect of the present disclosure, there is provided an aerosol generating device comprising a main body configured to receive an aerosol generating article, the main body comprising:

-   -   an outer casing having an inner surface and an outer surface;     -   an inner casing positioned inside the outer casing adjacent to         the inner surface;     -   an inner cover having an inner surface and an outer surface, the         inner cover being secured to a periphery of the inner casing to         define a space between the inner surface of the inner cover and         an inner surface of the inner casing;     -   an outer cover having an inner surface and an outer surface, the         outer cover being positioned over the inner cover;     -   wherein the outer surface of the outer casing and the outer         surface of the outer cover define an external surface of the         aerosol generating device, and a periphery of the outer cover         contacts a periphery of the outer casing so that the outer         surface of the outer cover lies substantially flush with the         outer surface of the outer casing to define a continuous         external surface.

The aerosol generating article may comprise an aerosol generating substrate.

The aerosol generating device is adapted to heat the aerosol generating substrate, without burning the aerosol generating substrate, to volatise at least one component of the aerosol generating substrate and thereby generate a vapour which cools and condenses to form an aerosol for inhalation by a user of the aerosol generating device. The aerosol generating device is a hand-held, portable, device, by which it is meant that a user is able to hold and support the device unaided, in a single hand.

In general terms, a vapour is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapour can be condensed to a liquid by increasing its pressure without reducing the temperature, whereas an aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. It should, however, be noted that the terms ‘aerosol’ and ‘vapour’ may be used interchangeably in this specification, particularly with regard to the form of the inhalable medium that is generated for inhalation by a user.

The close contact between the periphery of the outer cover and the periphery of the outer casing which results in the outer surfaces of these components lying substantially flush with each other, ensures that the aerosol generating device has a pleasing aesthetic appearance with a continuous external surface.

The aerosol generating device may have a proximal end and a distal end, and may have a longitudinal direction extending between the proximal end and the distal end. The aerosol generating device may have a front and may have a rear. The periphery of the outer cover may be curved in a transverse direction relative to the longitudinal direction between the front and rear of the aerosol generating device. The periphery of the outer casing may also be curved in the transverse direction. Thus, the flush outer surfaces of the outer cover and the outer casing may define a curved continuous external surface in the transverse direction between the front and rear of the aerosol generating device. The curved continuous external surface may further improve the aesthetic appearance of the aerosol generating device and may improve user comfort when holding and manipulating the aerosol generating device.

The main body may include a peripherally extending groove. The outer cover may include a peripherally extending rim and may include a peripherally extending collar which may be positioned inwardly with respect to the peripherally extending rim. The peripherally extending collar may be positioned in the peripherally extending groove and the peripherally extending rim may contact the periphery of the outer casing. The contact between the peripherally extending rim of the outer cover and the periphery of the outer casing ensures that the outer surface of the outer cover and the outer surface of the outer casing can lie flush to define the continuous external surface of the aerosol generating device, in particular without any other component parts of the main body, such as the inner casing and/or inner cover, being visible.

The peripherally extending collar may be spaced inwardly from the periphery of the outer casing. A close fit between the periphery of the outer cover and the periphery of the outer casing is thereby achieved, ensuring that the outer surfaces of the outer casing and the outer cover are flush and continuous.

The periphery of the outer casing may include a peripherally extending ledge. The peripherally extending rim of the outer cover may contact the peripherally extending ledge of the outer casing. A good alignment and close fit between the outer cover and the outer casing is thereby achieved.

The peripherally extending groove may have a depth which is greater than a depth of the peripherally extending collar. This ensures that the peripherally extending rim of the outer cover can directly contact the peripherally extending ledge of the outer casing and that there is no gap present between these components which might affect the aesthetic appearance of the aerosol generating device.

The peripherally extending groove may be defined between a peripheral portion of the inner cover and a peripheral portion of the outer casing. Thus, the peripherally extending groove is formed easily when the inner cover and the outer casing are assembled and does not need to be formed in any single component part during manufacture. Manufacture of the component parts of the aerosol generating device may, therefore, be simplified.

The aerosol generating device may further comprise at least one attachment element for releasably attaching the outer cover to the inner cover. The outer cover can, therefore, be easily removed and replaced, for example by a user of the aerosol generating device. This may allow the aerosol generating device to be personalised, for example by allowing outer covers having different colours and/or different textures to be attached by a user to the inner cover.

The attachment element may comprise a magnet. The use of a magnet may allow the outer cover to be reliably attached to, and detached from, the inner cover.

The aerosol generating device may further comprise a snap-fit connection structure for securing the inner cover to the inner casing. The inner cover is thereby reliably secured to the inner casing.

The inner casing may be secured in position inside the outer casing, adjacent to the inner surface of the outer casing.

The outer casing may comprise a metal, preferably aluminium. The use of a metal, and in particular aluminium, ensures that the aerosol generating device has a pleasing aesthetic appearance. Furthermore, the use of a metal allows the peripherally extending ledge to be accurately formed, for example by a suitable machining process, ensuring accurate alignment and a close fit between the peripherally extending rim of the outer cover and the peripherally extending ledge of the outer casing. In some embodiments, the outer casing may alternatively comprise a plastics material.

The outer cover may comprise a plastics material. The use of a plastics material may advantageously provide the outer cover with a sufficient amount of flexibility to enable the periphery of the outer cover to flex and conform to the periphery of the outer casing. This may further ensure that a close fit can be achieved between the periphery of the outer cover and the periphery of the outer casing. In some embodiments, the outer cover may alternatively comprise a metal.

The aerosol generating device may comprise an aerosol generating unit in the space defined between the inner surface of the inner cover and the inner surface of the inner casing. The aerosol generating unit may include a cavity for receiving an aerosol generating article. The aerosol generating unit may volatise at least one component of the aerosol generating substrate of the aerosol generating article, for example to generate a vapour which may cool and condense to form an aerosol for inhalation by a user of the aerosol generating device.

The aerosol generating unit may comprise a heater for heating the aerosol generating article, for example for heating an aerosol generating substrate positioned in the cavity. The term “heater” should be understood to mean any device for outputting thermal energy sufficient to form a vapour or aerosol by heating the aerosol generating substrate. The heater may be electrically powered and may include resistive track elements (optionally including insulating packaging), induction heating systems (e.g. including an electromagnet and high frequency oscillator), etc. The heater may be arranged around the outside of the cavity and, hence, the aerosol generating substrate, it may penetrate part way or fully into the cavity and, hence, the aerosol generating substrate, or any combination of these.

The heater may comprise a resistive heater. The resistive heater may comprise a resistive heating element or may comprise side wall(s) defining the cavity. The resistive heating element or the side wall(s) of the cavity may comprise an electrically resistive material. Examples of suitable electrically resistive materials include, but are not limited to, metals, metal alloys, electrically conductive ceramics, for example tungsten and alloys thereof, and composite materials comprising a metallic material and a ceramic material.

The heater may comprise an induction coil arranged to generate an alternating electromagnetic field for inductively heating an induction heatable susceptor. The induction coil may comprise a Litz wire or a Litz cable. It will, however, be understood that other materials could be used. The induction coil may extend around the cavity.

The induction coil could be substantially helical in shape. The circular cross-section of a helical induction coil may facilitate the insertion of an aerosol generating substrate, and more specifically an aerosol generating article including the aerosol generating substrate and optionally one or more inductively heatable susceptors, into the cavity and ensure uniform heating of the aerosol generating substrate. The inductively heatable susceptor(s) may comprise side wall(s) defining the cavity.

The inductively heatable susceptor(s) may comprise one or more, but not limited, of aluminium, iron, nickel, stainless steel and alloys thereof, e.g. Nickel Chromium or Nickel Copper. With the application of an electromagnetic field in its vicinity, the susceptor(s) may generate heat due to eddy currents and magnetic hysteresis losses resulting in a conversion of energy from electromagnetic to heat.

The induction coil may be arranged to operate in use with a fluctuating electromagnetic field having a magnetic flux density of between approximately 20 mT and approximately 2.0 T at the point of highest concentration.

The aerosol generating device may include a controller and the controller may include electronic circuitry. The aerosol generating device may include a power source, such as a battery. In embodiments which employ an induction heater, the power source and the electronic circuitry may be configured to operate at a high frequency. The power source and the electronic circuitry may be configured to operate at a frequency of between approximately 80 kHz and 500 kHz, possibly between approximately 150 kHz and 250 kHz, and possibly at approximately 200 kHz. The power source and the electronic circuitry could be configured to operate at a higher frequency, for example in the MHz range, depending on the type of inductively heatable susceptor that is used.

In one example, the aerosol generating substrate may comprise a non-liquid aerosol generating substrate, for example, any type of solid or semi-solid material. Example types of aerosol generating solids include powder, granules, pellets, shreds, strands, particles, gel, strips, loose leaves, cut leaves, cut filler, porous material, foam material or sheets. The aerosol generating substrate may comprise plant derived material and in particular, may comprise tobacco. It may advantageously comprise reconstituted tobacco.

Consequently, the aerosol generating device may equally be referred to as a “heated tobacco device”, a “heat-not-burn tobacco device”, a “device for vaporising tobacco products”, and the like, with this being interpreted as a device suitable for achieving these effects. Thus, the aerosol generating substrate may be referred to as a t-vapour substrate. The features disclosed herein are equally applicable to devices which are designed to vaporise any aerosol generating substrate.

The aerosol generating article may comprise a paper wrapper which circumscribes the aerosol generating substrate. The aerosol generating article may be formed substantially in the shape of a stick, and may broadly resemble a cigarette, having a tubular region with an aerosol generating substrate arranged in a suitable manner. The aerosol generating article may include a filter, for example comprising cellulose acetate fibres. The filter may be in abutting coaxial alignment with the aerosol generating substrate. One or more vapour collection regions, vapour cooling regions, and other structures may also be included in some designs.

The aerosol generating substrate may comprise an aerosol-former. Examples of aerosol-formers include polyhydric alcohols and mixtures thereof such as glycerine and/or propylene glycol. Typically, the aerosol generating substrate may comprise an aerosol-former content of between approximately 5% and approximately 50% on a dry weight basis. In some embodiments, the aerosol generating substrate may comprise an aerosol-former content of between approximately 10% and approximately 20% on a dry weight basis, and possibly approximately 15% on a dry weight basis.

In another example, the aerosol generating substrate may comprise an aerosol generating liquid. The aerosol generating liquid may comprise polyhydric alcohols and mixtures thereof such as glycerine and/or propylene glycol. The aerosol generating liquid may contain nicotine and may, therefore, be designated a nicotine-containing liquid. The aerosol generating liquid may contain one or more additives, such as a flavouring.

Upon heating, the aerosol generating substrate, whether non-liquid or liquid, may release volatile compounds. The volatile compounds may include nicotine or flavour compounds such as tobacco flavouring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is diagrammatic perspective view of an aerosol generating device according to the present disclosure;

FIG. 2 is a diagrammatic cross-sectional view from a side of the aerosol generating device of FIG. 1 , shown with an aerosol generating article ready to be loaded into the aerosol generating device;

FIG. 3 is a diagrammatic perspective view of the aerosol generating device of FIG. 1 , shown with the aerosol generating article loaded into the aerosol generating device;

FIG. 4 is a diagrammatic cross-sectional view from the side of the aerosol generating device of FIG. 1 , shown with the aerosol generating article loaded into the aerosol generating device;

FIG. 5 is a diagrammatic perspective view of the aerosol generating device of FIG. 1 , illustrating the continuous external surface formed by the outer surfaces of an outer casing and an outer cover;

FIG. 6 is a diagrammatic exploded view of the aerosol generating device of FIG. 1 , illustrating component parts of the aerosol generating device;

FIG. 7 is a diagrammatic perspective view of the aerosol generating device of FIG. 1 , with the outer cover detached from the aerosol generating device; and

FIG. 8 is an enlarged diagrammatic cross-sectional view of the periphery of the aerosol generating device of FIG. 1 , illustrating the continuous external surface formed by the outer surfaces of the outer casing and the outer cover.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings.

Referring initially to FIGS. 1 to 4 , an aerosol generating device 10 comprises a main body 12 housing various components of the aerosol generating device 10. In the illustrated example, the main body 12 has an irregular shape, but it will be appreciated that any shape is possible, so long as it is sized to fit the components described in the various embodiments set out herein and to be comfortably held by a user unaided, in a single hand.

A first end 14 of the aerosol generating device 10, shown towards the bottom of each of FIGS. 1 to 4 , is described for convenience as a distal, bottom, base or lower end of the aerosol generating device 10. A second end 16 of the aerosol generating device 10, shown towards the top of each of FIGS. 1 to 4 , is described as a proximal, top or upper end of the aerosol generating device 10. During use, the user typically orients the aerosol generating device 10 with the first end 14 downward and/or in a distal position with respect to the user's mouth and the second end 16 upward and/or in a proximate position with respect to the user's mouth.

Referring also to FIGS. 5 and 6 , the main body 12 comprises: an outer casing 18 having an inner surface 18 a and an outer surface 18 b; an inner casing 20 having an inner surface 20 a and an outer surface 20 b; an inner cover 22 having an inner surface 22 a and an outer surface 22 b; and an outer cover 24 having an inner surface 24 a and an outer surface 24 b. The outer surface 18 b of the outer casing 18 and the outer surface 24 b of the outer cover 24 together define an external surface 48 of the aerosol generating device 10.

The aerosol generating device 10 includes an aerosol generating unit 26 which is positioned in a space 27 defined between the inner surface 20 a of the inner casing 20 and the inner surface 22 a of the inner cover 22. The aerosol generating unit 26 comprises a heating chamber 28 defining a cavity 30 having a substantially cylindrical cross-section for receiving an aerosol generating article 100. The aerosol generating unit 26 further comprises a power source 32, for example one or more batteries which may be rechargeable, and a controller (not shown). The aerosol generating unit 26 may comprise a chassis on which the heating chamber 28, power source 32 and controller are mounted. These components may form a single unit.

The heating chamber 28 is open towards the second end 16 of the aerosol generating device 10. In other words, the heating chamber 28 has an open first end 36 towards the second end 16 of the aerosol generating device 10. The heating chamber 28 is typically held spaced apart from the inner surfaces 20 a, 22 a of the inner casing 20 and the inner cover 22 to inhibit heat transfer to the main body 12. In order to further increase the thermal isolation of the heating chamber 28, the heating chamber 28 may be surrounded by insulation, for example a fibrous or foam material, such as cotton wool, aerogel or gas, or in other examples vacuum insulation may be provided.

The aerosol generating device 10 can further include a sliding cover 40 movable transversely between a closed position (see FIGS. 1, 2 and 5 ) in which it covers the open first end 36 of the heating chamber 28 to prevent access to the heating chamber 28 and an open position (see FIGS. 3 and 4 ) in which it exposes the open first end 36 of the heating chamber 28 to provide access to the heating chamber 28. The sliding cover 40 can be biased to the closed position in some embodiments.

The heating chamber 28, and specifically the cavity 30, is arranged to receive a correspondingly shaped generally cylindrical or rod-shaped aerosol generating article 100 as illustrated in FIGS. 2 to 4 . Typically, the aerosol generating article 100 comprises a pre-packaged aerosol generating substrate 102. The aerosol generating article 100 is a disposable and replaceable article (also known as a “consumable”) which may, for example, contain tobacco as the aerosol generating substrate 102. The aerosol generating article 100 has a proximal end 104 (or mouth end) and a distal end 106. The aerosol generating article 100 further comprises a mouthpiece segment 108 positioned downstream of the aerosol generating substrate 102. The aerosol generating substrate 102 and the mouthpiece segment 108 are arranged in coaxial alignment inside a wrapper 110 (e.g., a paper wrapper) to hold the components in position to form the rod-shaped aerosol generating article 100.

The mouthpiece segment 108 can comprise one or more of the following components (not shown in detail) arranged sequentially and in co-axial alignment in a downstream direction, in other words from the distal end 106 towards the proximal (mouth) end 104 of the aerosol generating article 100: a cooling segment, a center hole segment and a filter segment. The cooling segment typically comprises a hollow paper tube having a thickness which is greater than the thickness of the wrapper 110. The center hole segment may comprise a cured mixture containing cellulose acetate fibres and a plasticizer, and functions to increase the strength of the mouthpiece segment 108. The filter segment typically comprises cellulose acetate fibres and acts as a mouthpiece filter. As heated vapour flows from the aerosol generating substrate 102 towards the proximal (mouth) end 104 of the aerosol generating article 100, the vapour cools and condenses as it passes through the cooling segment and the center hole segment to form an aerosol with suitable characteristics for inhalation by a user through the filter segment.

In other embodiments, the heating chamber 28 can be arranged to receive the aerosol generating substrate 102 in other forms, such as loose shredded material, solid material packaged in other ways, or as an aerosol generating liquid packaged in an aerosol generating article 100.

The heating chamber 28 has a side wall 42 extending between a base 44 (located at a second end 38 of the heating chamber) and the open first end 36. The side wall 42 and the base 44 are connected to each another and can be integrally formed as a single piece. In the illustrated embodiment, the side wall 42 is tubular and, more specifically, cylindrical. However, in other embodiments the side wall 42 can have other suitable shapes, such as a tube with an elliptical or polygonal cross section. In yet further embodiments, the side wall 42 can be tapered.

In the illustrated embodiment, the base 44 of the heating chamber 28 is closed, e.g. sealed or air-tight. That is, the heating chamber 28 is cup-shaped. This can ensure that air drawn from the open first end 36 is prevented by the base 44 from flowing out of the second end 38 and is instead guided through the aerosol generating substrate 102. It can also ensure that a user inserts the aerosol generating article 100 into the heating chamber 28 an intended distance and no further.

The aerosol generating unit 26 includes a heater 46 for heating the aerosol generating substrate 102 without burning the aerosol generating substrate 102. In the illustrated embodiment, the heater 46 is a resistive heater which coextends with the side wall 42 of the heating chamber 28. Other types and configurations of heater 46 can, of course, be used as discussed earlier in this specification. In the illustrated embodiment, the heater 46 is mounted on a surface of the tubular side wall 42 facing away from an interior volume of the heating chamber 28. This can help to protect the heater 46 from damage as the aerosol generating article 100 is inserted into the cavity 30 defined by the heating chamber 28.

In the first embodiment, the aerosol generating device 10, and more particularly the heater 46 of the aerosol generating unit 26, is electrically powered. That is, the heater 46 is arranged to heat the aerosol generating substrate 102 using electrical power. For this purpose, the power source 32 is coupled to the controller (not shown). The controller is in turn coupled to the heater 46. A user operates the aerosol generating device 10 using control means (not shown), arranged to cause coupling and uncoupling of the power source 32 to the heater 46 via the controller.

In order to use the aerosol generating device 10, a user displaces the sliding cover 40 (if present) from the closed position shown in FIGS. 1, 2 and 5 to the open position shown in FIGS. 3 and 4 . The user then inserts an aerosol generating article 100 through the open first end 36 into the heating chamber 28, so that the aerosol generating substrate 102 is received in the cavity 30 and so that the proximal end 104 of the aerosol generating article 100 is positioned at the open first end 36 of the heating chamber 28, with at least part of the mouthpiece segment 108 projecting from the open first end 36 to permit engagement by a user's lips.

Upon activation of the aerosol generating device 10 by a user, an electric current is supplied to the heater 46 causing it to heat up. The heat from the heater 46 is transferred through the side wall 42 of the heating chamber 28 to the adjacent aerosol generating substrate 102 of an aerosol generating article 100 positioned in the heating chamber 28, for example by conduction, radiation and convection. This results in heating of the aerosol generating substrate 102 and a vapour is thereby generated. The generated vapour cools and condenses to form an aerosol for inhalation by a user of the aerosol generating device 10 through the mouthpiece segment 108, and more particularly through a filter segment. The vaporisation of the aerosol generating substrate 102 is facilitated by the addition of air from the surrounding environment through the open first end 36 of the heating chamber 28, the airflow being between the wrapper 110 of the aerosol generating article 100 and the inner surface of the cylindrical side wall 42.

As noted above, the main body 12 comprises an outer casing 18, an inner casing 20, an inner cover 22 and an outer cover 24. When these components (shown separately in FIG. 6 ) are fully assembled as shown in FIGS. 1, 3 and 5 to form the main body 12, the inner casing 20 is positioned inside the outer casing 18, more specifically with the outer surface 20 b of the inner casing 20 positioned adjacent to the inner surface 18 a of the outer casing 18. In some embodiments, the inner casing 20 can be secured in position inside the outer casing 18 by a snap-fit connection structure or in any other suitable manner.

The inner casing 20 has a periphery 20 c. The inner cover 22 also has a periphery 22 c. The periphery 22 c of the inner cover 22 is secured to the periphery 20 c of the inner casing 20, for example by a snap-fit connection structure 60 as shown in FIG. 8 or other suitable connection means, thereby defining the space 27 between the inner surfaces 20 a, 22 a of the inner casing 20 and the inner cover 22 in which the aerosol generating unit 26 is accommodated.

The outer cover 24 is positioned over the inner cover 22 with the outer surface 22 b of the inner cover 22 and the inner surface 24 a of the outer cover 24 positioned adjacent to each other. The outer cover 24 has a periphery 24 c and contacts a periphery 18 c of the outer casing 18. As will be apparent from FIGS. 3 and 5 in particular, no part of the inner casing 20 or the inner cover 22 is visible externally of the aerosol generating device 10 when the outer cover 24 is positioned over the inner cover 22 with its periphery 24 c in contact with the periphery 18 c of the outer casing 18.

The contact between the respective peripheries 24 c, 18 c of the outer cover 24 and the outer casing 18 is such that the outer surface 24 b of the outer cover 24 lies substantially flush with the outer surface 18 b of the outer casing 18 to define a continuous external surface 48 of the aerosol generating device 10. Referring to FIG. 8 , it can be seen that the periphery 24 c of the outer cover 24 and the periphery 18 c of the outer casing 18 are both curved in a transverse direction of the aerosol generating device 10, and consequently that the continuous external surface 48 defined by the flush outer surfaces 24 b, 18 b is also curved in the transverse direction. Thus, the aerosol generating device has a smooth and substantially continuous curved outer profile at the junction between the peripheries 24 c, 18 c of the outer cover 24 and the outer casing 18, for example resulting in a curved outer profile which is ergonomic and aesthetically pleasing.

The outer casing 18 typically comprises a metal, for example aluminium, whilst the outer cover 24 typically comprises a plastics material. Alternatively, the outer casing 18 may comprise a plastics material and/or the outer cover 24 may comprise a metal.

The outer cover 24 is attached to the inner cover 22 of the aerosol generating device 10 and the attachment can be releasable to allow the outer cover 24 to be removed from the aerosol generating device 10 as shown in FIG. 7 . The aerosol generating device 10 typically includes one or more attachment elements 50, for example magnets comprising a magnetic coupling element 52 and a magnetic counter-coupling element 54, which provide the releasable attachment between the outer cover 24 and the inner cover 22. Thus, although there is contact between the periphery 24 c of the outer cover 24 and the periphery 18 c of the outer casing 18, the outer cover 24 and outer casing 18 are secured to each other indirectly, by means of the inner casing 20 and the inner cover 22.

Referring again to FIG. 8 , the periphery 18 c of the outer casing 18 includes a peripherally extending ledge 56 which extends in a transverse plane. In an example embodiment, the peripherally extending ledge 56 may have a transverse dimension of approximately 0.7 mm. The outer cover 24 includes a peripherally extending rim 58 which also extends in a transverse plane. The peripherally extending rim 58 contacts, and rests on, the peripherally extending ledge 56 thus ensuring that there is a close fit between the peripheries 24 c, 18 c of the outer cover 24 and the outer casing 18, such that the respective outer surfaces 24 b, 18 b lie substantially flush with each other to define the continuous external surface 48 of the aerosol generating device 10.

The aerosol generating device 10 includes a peripherally extending groove 62 which is defined between a peripheral portion 64 of the inner cover 22 and a peripheral portion 66 of the outer casing 18. The outer cover 24 includes a peripherally extending collar 68 which is positioned inwardly with respect to the peripherally extending rim 58 and spaced inwardly with respect to the periphery 18 c of the outer casing 18. When the outer cover 24 is attached to the inner cover 22, the peripherally extending collar 68 is positioned in the peripherally extending groove 62. The peripherally groove 62 has a depth which is greater than a depth of the peripherally extending collar 68, thereby ensuring that there is no contact between the peripherally extending collar 68 and the base of the peripherally extending groove 62 and, thus, that the peripherally extending rim 58 of the outer cover 24 can make direct contact with the peripherally extending ledge 56 of the outer casing 18. As will be apparent from FIG. 8 , a small gap, approximately 0.15 mm in an example embodiment, is present between an inwardly facing surface 70 of the outer casing 18 and an opposing outwardly facing surface 72 of the peripherally extending collar 68. This gap ensures that the peripherally extending collar 68 can be reliably located in the peripherally extending groove 62 when the outer cover 24 is attached to the inner cover 22, thus ensuring that the peripherally extending rim 58 of the outer cover 24 can directly contact the peripherally extending ledge 56 of the outer casing 18 around the entire periphery of the aerosol generating device 10 and in turn ensuring that there is a satisfactory fit between the periphery 24 c of the outer cover 24 and the periphery 18 c of the outer casing 18.

Although exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications may be made to those embodiments without departing from the scope of the appended claims. Thus, the breadth and scope of the claims should not be limited to the above-described exemplary embodiments.

Any combination of the above-described features in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. 

1. An aerosol generating device comprising a main body configured to receive an aerosol generating article, the main body comprising: an outer casing having an inner surface and an outer surface; an inner casing positioned inside the outer casing adjacent to the inner surface; an inner cover having an inner surface and an outer surface, the inner cover being secured to a periphery of the inner casing to define a space between the inner surface of the inner cover and an inner surface of the inner casing; an outer cover having an inner surface and an outer surface, the outer cover being positioned over the inner cover; wherein the outer surface of the outer casing and the outer surface of the outer cover define an external surface of the aerosol generating device, and a periphery of the outer cover contacts a periphery of the outer casing so that the outer surface of the outer cover lies substantially flush with the outer surface of the outer casing to define a continuous external surface.
 2. The aerosol generating device according to claim 1, wherein the aerosol generating device has a proximal end, a distal end, and a longitudinal direction extending between the proximal end and the distal end, and wherein the periphery of the outer cover is curved in a transverse direction relative to the longitudinal direction between a front and a rear of the aerosol generating device and the periphery of the outer casing is also curved in said transverse direction so that the flush outer surfaces of the outer cover and the outer casing define a curved continuous external surface in said transverse direction.
 3. The aerosol generating device according to claim 1, wherein: the main body includes a peripherally extending groove; the outer cover includes a peripherally extending rim and a peripherally extending collar positioned inwardly with respect to the peripherally extending rim; and the peripherally extending collar is positioned in the peripherally extending groove and the peripherally extending rim contacts the periphery of the outer casing.
 4. The aerosol generating device according to claim 3, wherein the peripherally extending collar is spaced inwardly from the periphery of the outer casing.
 5. The aerosol generating device according to claim 3, wherein the periphery of the outer casing includes a peripherally extending ledge and the peripherally extending rim of the outer cover contacts the peripherally extending ledge of the outer casing.
 6. The aerosol generating device according to claim 3, wherein the peripherally extending groove has a depth which is greater than a depth of the peripherally extending collar.
 7. The aerosol generating device according to claim 3, wherein the peripherally extending groove is defined between a peripheral portion of the inner cover and a peripheral portion of the outer casing.
 8. The aerosol generating device according to claim 1, further comprising at least one attachment element for releasably attaching the outer cover to the inner cover.
 9. The aerosol generating device according to claim 8, wherein the attachment element comprises a magnet.
 10. The aerosol generating device according to claim 1, further comprising a snap-fit connection structure for securing the inner cover to the inner casing.
 11. The aerosol generating device according to claim 1, wherein the outer casing comprises a metal.
 12. The aerosol generating device according to claim 1, wherein the outer cover comprises a plastics material.
 13. The aerosol generating device according to claim 1, wherein the aerosol generating device comprises an aerosol generating unit in the space defined between the inner surface of the inner cover and the inner surface of the inner casing, the aerosol generating unit including a cavity for receiving an aerosol generating article.
 14. The aerosol generating device of claim 11, wherein the metal comprises aluminium. 